Genetic Testing Targets Therapies to Defeat Prostate Cancer

Genetic testing in men with advanced prostate cancer can spot genetic mutations that could point the way to targeting men who would benefit from new precision treatments.

Researchers at London's The Institute of Cancer Research found that about 12 percent of men with advanced prostate cancer had inherited gene mutations in genes that normally repair DNA damage. The mutated genes include the breast cancer gene BRCA2, known as the "Angelina Jolie" gene, which may cause 1 in 20 cases of prostate cancer.

Their discovery could lead to a simple saliva test that could determine the best course of treatment for men as soon as they are diagnosed with the disease.

The researchers examined the DNA code of 20 genes known to be involved in DNA repair in 692 men with advanced prostate cancer. They discovered that about 12 percent had at least one type of gene mutation. The most common defective gene was BRCA2 which was mutated in 5 percent of the men.

The best treatment for these men could be a new type of drug called PARP inhibitors. These drugs inhibit the enzyme poly ADP ribose polymerase (PARP). Studies have found that blocking PARP kills tumor cells where the ability to repair DNA is impaired.

"Our study has shown that a significant proportion of men with advanced prostate cancer are born with DNA repair mutations — and this could have important implications for patients," said Johann de Bono of The Institute of Cancer Research.

"Genetic testing for these mutations could identify men with advanced prostate cancer who may benefit from precision treatment," he continued. "We could offer these men drugs such as PARP inhibitors, which are effective in patients with certain DNA repair mutations and are showing important anti-tumor activity in ongoing clinical trials."

The research is published in The New England Journal of Medicine.